It will be continued with the connective tissue analysis. It has been shown, that sympathectomized arteries exhibited an increase in collagen synthesis. Since the collagen content and the change in mechanical properties do not change proportionally, new methods will be appled to differentiate between old and newly formed collagen. We will inject repeatedly newly born rabbits with L-3H-proline for three months. In the following three months half of the rabbits will be sympathectomized. Arteries will be analyzed for connective tissue content on the basis of the hydroxyproline content. The relationship between hydroxyproline and the radioactivity of the aortic sample will express the ratio between old and newly formed collagen. Decrease in specific radioactivity from hydroxyproline of collagen at the presence of high collagen content indicates increased collagen formation when compared with control rabbits. These data will also complement our experiments performed with arteries partially digested with collagenase and elastase. While we established that long term sympathectomy leads to profound changes in the metabolic activity of the arterial wall as a next step we plan to determine which component of the sympathetic nerve activity is related more closely to metabolic changes. Can exactly the same effect be achieved with synpatholytics as with sympathectomy? If so, is there a difference between alpha and beta blockers? Therefore, we plant to administer chronically reserpine, dibenzyline and propranalol and analyze the arteries from treated rabbits in the same manner as we did after long term chemical sympathectomy.